This invention relates to a support loaded with a base material, its method of manufacture and a process in which it is used for making 4-aminodiphenylamine (4-ADPA), an important intermediate in the production of substituted paraphenylenediamine (PPD) antidegradants for polymers, especially rubber.
It is known to prepare 4-ADPA by way of a nucleophilic aromatic substitution mechanism, wherein an aniline derivative replaces halide. This method involves preparation of a 4-ADPA intermediate, namely 4-nitrodiphenylamine (4-NDPA) followed by reduction of the nitro moiety. The 4-NDPA is prepared by reacting p-chloronitrobenzene with an aniline derivative, such as formanilide or an alkali metal salt thereof, in the presence of an acid acceptor or neutralizing agent, such as potassium carbonate, and, optionally, utilizing a catalyst. See, for example, U.S. Pat. Nos. 4,187,248; 4,683,332; 4,155,936; 4,670,595; 4,122,118; 4,614,817; 4,209,463; 4,196,146; 4,187,249; 4,140,716. This method is disadvantageous in that the halide that is displaced is corrosive to the reactors and appears in the waste stream and must therefore be disposed of at considerable expense. Furthermore, use of an aniline derivative such as formanilide, and use of p-chloro-nitrobenzene, requires additional manufacturing equipment and capabilities to produce such starting materials from aniline and nitrobenzene, respectively.
It is also known to prepare 4-ADPA from the head-to-tail coupling of aniline. See, for example, G.B. 1,440,767 and U.S. Pat. No. 4,760,186. This method is disadvantageous in that the yield of 4-ADPA is not acceptable for a commercial process. It is also known to decarboxylate a urethane to produce 4-NDPA. See U.S. Pat. No. 3,847,990. However, such method is not commercially practical in terms of cost and yield.
It is known to prepare 4-ADPA by hydrogenating p-nitrosodiphenylhydroxylamine which can be prepared by catalytic dimerization of nitrosobenzene utilizing, as a reducing agent, aliphatic compounds, benzene, naphthalene or ethylenically unsaturated compounds. See for example, U.S. Pat. Nos. 4,178,315 and 4,404,401. It is also known to prepare p-nitrosodiphenylamine from diphenylamine and an alkyl nitrate in the presence of excess hydrogen chloride. See, for example, U.S. Pat. Nos. 4,518,803 and 4,479,008.
It is also known to produce 4-nitrosodiphenylamine by reacting acetanilide and nitrobenzene in DMSO in the presence of sodium hydroxide and potassium carbonate at 80xc2x0 C. for 5 hours. See Ayyangar et al., Tetrahedron Letters, Vol. 31, No. 22, pp. 3217-3220 (1990). However, the yield of 4-nitrosodiphenylamine is low and is therefore not commercially practical. Furthermore, such method requires utilization of an aniline derivative, namely, acetanilide, and therefore increases the cost of the starting materials.
The production of 4-nitrosodiphenylamine in very low yield, by reacting aniline with nitrobenzene has long been known to the art. See Wohl, Chemische Berichte, 36, p. 4135 (1903) and Chemische Berichte, 34, p. 2442 (1901).
It is also known to prepare 4-ADPA by the successive steps of a) reacting aniline with nitrobenzene in the presence of a base, under controlled conditions to produce a mixture containing the salts of 4-nitrodiphenylamine and of 4-nitrosodiphenylamine and then b) hydrogenating the salts. U.S. Pat. Nos. 5,117,063 and 5,453,541 disclose such a process.
U.S. Pat. No. 5,420,354, shows another process for the preparation of p-aminodiphenylamine by contacting nitrobenzene with hydrogen and aniline in the presence of a hydrogenation catalyst, a hydrogenation inhibitor and an acid catalyst. While this latter process is described as a one-step process, selectivity to the desired product is relatively low.
The process of the present invention produces an intermediate of 4-ADPA or 4-ADPA directly in a novel manner employing a zeolite support loaded with a base material.
In one embodiment, the invention comprises a composition suitable for use in a reaction zone where aniline is reacted with nitrobenzene to obtain intermediates of 4-aminodiphenylamine. The composition comprises a solid support having interior channels with base material employed in the reaction loaded into the channels. The cross-sectional dimensions of the channels are such as to provide a restricted transition state with regard to the reaction and to improve the selectivity of the reaction in favor of the intermediates.
In another embodiment, where the above solid support is a zeolite, the invention comprises a method of making the above composition comprising:
(a) ion exchanging zeolite with base material by contacting the zeolite with an aqueous solution of the base material;
(b) drying the zeolite recovered from step (a);
(c) adding additional base material in aqueous solution to the dried zeolite from step (b) to obtain zeolite slurry; and
(d) recovering zeolite from the zeolite slurry having the desired loading of base material.
In a further embodiment, this invention provides a process for preparing an intermediate of 4-ADPA by reacting aniline with nitrobenzene in a reaction zone containing a solid upport loaded with a base material. The solid support has interior channels with base material employed in the reaction loaded into the channels. The cross-sectional dimensions of the channels are such as to provide a restricted transition state with regard to the reaction and to improve the selectivity of the reaction in favor of the intermediate.
In still another embodiment, the present invention is a one-step process for preparing 4-aminodiphenylamine (4-ADPA) comprising charging nitrobenzene into a reaction zone under hydrogen pressure and in the presence of a base material loaded on a solid support and a hydrogenation catalyst. The solid support has interior channels with base material employed in the reaction loaded into the channels. The cross-sectional dimensions of the channels are such as to provide a restricted transition state with regard to the reaction and to improve the selectivity of the reaction in favor of 4-ADPA.
An yet another embodiment, the invention is a process for the hydrogenation of nitrobenzene to 4-aminodiphenylamine (4-ADPA) comprising:
a) preparing a reaction zone by supplying a strong organic base loaded on a solid support and a hydrogenation catalyst, the solid support having interior channels with base material employed in the reaction loaded into the channels; the cross-sectional dimensions of the channels are such as to provide a restricted transition state with regard to the reaction and to improve the selectivity of the reaction in favor of 4-ADPA;
(b) applying a flow of hydrogen at a pressure sufficient to force the conversion of nitrobenzene to 4-ADPA intermediates and to further hydrogenate the intermediates to 4-ADPA;
(c) charging to the reaction zone an amount of aniline and nitrobenzene such that the molar ratio of aniline to nitrobenzene in the reaction zone is not greater than about 5.0, and that the molar ratio of nitrobenzene to the strong organic base is not greater than about 18.0; and
(d) conducting the hydrogenation reaction for the conversion of nitrobenzene to 4-ADPA as a one-step process.
Other embodiments of the present invention encompass further details relating to the composition of loaded solid support, methods of making the loaded support and conditions and process details concerning the use of the loaded support, all of which are hereinafter disclosed in the following discussion of each of those facets of the invention.